Type the sugars fructose used to sweeten soft drinks, cakes and chocolate, sugar is the most "lethal", said the scientists warn.
Fructose can increase bad cholesterol and the risk of diabetes that lead to heart attack or stroke.
Although fructose is also found in fruits, the effects of natural fructose can be neutralized easily by the body, in contrast to fructose in processed foods as well as sweet menuman.
Fructose is added to sweeten food products and beverages judged to be worse for the body than glucose.
In the study, rats fed a fructose water for two months experienced a surge in weight than rats given sugar water. The rats also had higher levels of harmful fats in the bloodstream and unhealthy condition of the arteries.
Food expert Professor Marta Alegret from the University of Barcelona advise people to avoid products with added fructose.
According to him, the amount of fructose ingested in natural fruit is usually lower than that consumed in sugary drinks.
"Fructose in food and beverage is a type of sugar that can trigger metabolic disease and vascular disease," he added.
Prof Alegret and colleagues also found fructose have an effect on how the body's main artery, the aorta, work. "Fructose produces negative effects for relaxation right complicates the aorta," he explained.
The rats given fructose also showed changes in their heart health and gain weight faster.
Prof Alegret revealed that this could cause serious problems in the future, which means we have to reduce the fructose.
According to experts, sweets to be significantly reduced is sweets, cakes, biscuits, chocolate and soft drinks, and other processed foods and beverages containing fructose.